A driveline of a hybrid vehicle may include and engine and a motor that are selectively coupled together. The engine and motor may be selectively coupled together via a disconnect clutch. The engine and motor may also be coupled to an automatic transmission. The automatic transmission may include a torque converter and a plurality of fixed gear ratios. The engine and motor may supply torque to vehicle wheels via the transmission to propel the hybrid vehicle. During a course of driving, the transmission may switch gears so that vehicle acceleration and energy efficiency may be improved. However, a driver may sense a difference in vehicle acceleration across transmission gear shifting or experience different shift feel when the disconnect clutch is closed as compared to when the disconnect clutch is open.
The inventors herein have recognized the above-mentioned issues and have developed a method for operating a hybrid powertrain, comprising: operating a drivetrain with a first inertia and adjusting a torque converter impeller torque during transmission gear shifting in response to the first inertia; and operating the drivetrain with a second inertia and adjusting the torque converter impeller torque during transmission gear shifting in response to the second inertia.
By adjusting a torque converter impeller torque in response to different driveline inertias, it may be possible to improve transmission gear shifting of a hybrid vehicle. For example, impeller torque during a first set of conditions can be adjusted to a greater torque when driveline inertia is at a maximum driveline inertia (e.g., an inertia that includes an engine and a motor). Further, during conditions that are substantially the same as the first set of conditions, excluding the driveline inertia, impeller torque can be adjusted to torque that is less than during the first set of conditions when the driveline inertia is less than the maximum driveline inertia (e.g., an inertia including the motor and excluding the engine). In this way, torque converter impeller torque may be adjusted to account for driveline inertia changes that result from opening and closing the driveline disconnect clutch.
The present description may provide several advantages. Specifically, the approach may improve vehicle shifting. Further, the approach may reduce clutch wear. Further still, the approach may improve vehicle drivability.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.